Auto merge of rust-lang#131343 - compiler-errors:remove-combine-fields, r=<try>

Remove `CombineFields`

This conflicts with rust-lang#131263, but if this one lands first then perhaps rust-lang#131263 could then go ahead and remove all the branching on solver in `TypeRelating`. We could perhaps then rename `TypeRelating` to `OldSolverRelating` or something, idk.

r? lcnr

Author: bors

compiler/rustc_hir_typeck/src/coercion.rs

@@ -141,7 +141,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
             let at = self.at(&self.cause, self.fcx.param_env);
 
             let res = if self.use_lub {
-                at.lub(DefineOpaqueTypes::Yes, b, a)
+                at.lub(b, a)
             } else {
                 at.sup(DefineOpaqueTypes::Yes, b, a)
                     .map(|InferOk { value: (), obligations }| InferOk { value: b, obligations })
@@ -1190,13 +1190,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     (ty::FnDef(..), ty::FnDef(..)) => {
                         // Don't reify if the function types have a LUB, i.e., they
                         // are the same function and their parameters have a LUB.
-                        match self.commit_if_ok(|_| {
-                            self.at(cause, self.param_env).lub(
-                                DefineOpaqueTypes::Yes,
-                                prev_ty,
-                                new_ty,
-                            )
-                        }) {
+                        match self
+                            .commit_if_ok(|_| self.at(cause, self.param_env).lub(prev_ty, new_ty))
+                        {
                             // We have a LUB of prev_ty and new_ty, just return it.
                             Ok(ok) => return Ok(self.register_infer_ok_obligations(ok)),
                             Err(_) => {
@@ -1239,7 +1235,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             let (a_sig, b_sig) = self.normalize(new.span, (a_sig, b_sig));
             let sig = self
                 .at(cause, self.param_env)
-                .lub(DefineOpaqueTypes::Yes, a_sig, b_sig)
+                .lub(a_sig, b_sig)
                 .map(|ok| self.register_infer_ok_obligations(ok))?;
 
             // Reify both sides and return the reified fn pointer type.
@@ -1330,9 +1326,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 );
 
                 return Err(self
-                    .commit_if_ok(|_| {
-                        self.at(cause, self.param_env).lub(DefineOpaqueTypes::Yes, prev_ty, new_ty)
-                    })
+                    .commit_if_ok(|_| self.at(cause, self.param_env).lub(prev_ty, new_ty))
                     .unwrap_err());
             }
         }
@@ -1344,13 +1338,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     Err(e)
                 } else {
                     Err(self
-                        .commit_if_ok(|_| {
-                            self.at(cause, self.param_env).lub(
-                                DefineOpaqueTypes::Yes,
-                                prev_ty,
-                                new_ty,
-                            )
-                        })
+                        .commit_if_ok(|_| self.at(cause, self.param_env).lub(prev_ty, new_ty))
                         .unwrap_err())
                 }
             }

compiler/rustc_infer/src/infer/at.rs

@@ -25,12 +25,13 @@
 //! sometimes useful when the types of `c` and `d` are not traceable
 //! things. (That system should probably be refactored.)
 
+use relate::lattice::{LatticeOp, LatticeOpKind};
 use rustc_middle::bug;
 use rustc_middle::ty::{Const, ImplSubject};
 
 use super::*;
+use crate::infer::relate::type_relating::TypeRelating;
 use crate::infer::relate::{Relate, StructurallyRelateAliases, TypeRelation};
-use crate::traits::Obligation;
 
 /// Whether we should define opaque types or just treat them opaquely.
 ///
@@ -108,14 +109,16 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     where
         T: ToTrace<'tcx>,
     {
-        let mut fields = CombineFields::new(
+        let mut op = TypeRelating::new(
             self.infcx,
             ToTrace::to_trace(self.cause, expected, actual),
             self.param_env,
             define_opaque_types,
+            StructurallyRelateAliases::No,
+            ty::Contravariant,
         );
-        fields.sup().relate(expected, actual)?;
-        Ok(InferOk { value: (), obligations: fields.into_obligations() })
+        op.relate(expected, actual)?;
+        Ok(InferOk { value: (), obligations: op.into_obligations() })
     }
 
     /// Makes `expected <: actual`.
@@ -128,14 +131,16 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     where
         T: ToTrace<'tcx>,
     {
-        let mut fields = CombineFields::new(
+        let mut op = TypeRelating::new(
             self.infcx,
             ToTrace::to_trace(self.cause, expected, actual),
             self.param_env,
             define_opaque_types,
+            StructurallyRelateAliases::No,
+            ty::Covariant,
         );
-        fields.sub().relate(expected, actual)?;
-        Ok(InferOk { value: (), obligations: fields.into_obligations() })
+        op.relate(expected, actual)?;
+        Ok(InferOk { value: (), obligations: op.into_obligations() })
     }
 
     /// Makes `expected == actual`.
@@ -167,45 +172,16 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     where
         T: Relate<TyCtxt<'tcx>>,
     {
-        let mut fields = CombineFields::new(self.infcx, trace, self.param_env, define_opaque_types);
-        fields.equate(StructurallyRelateAliases::No).relate(expected, actual)?;
-        Ok(InferOk {
-            value: (),
-            obligations: fields
-                .goals
-                .into_iter()
-                .map(|goal| {
-                    Obligation::new(
-                        self.infcx.tcx,
-                        fields.trace.cause.clone(),
-                        goal.param_env,
-                        goal.predicate,
-                    )
-                })
-                .collect(),
-        })
-    }
-
-    /// Equates `expected` and `found` while structurally relating aliases.
-    /// This should only be used inside of the next generation trait solver
-    /// when relating rigid aliases.
-    pub fn eq_structurally_relating_aliases<T>(
-        self,
-        expected: T,
-        actual: T,
-    ) -> InferResult<'tcx, ()>
-    where
-        T: ToTrace<'tcx>,
-    {
-        assert!(self.infcx.next_trait_solver());
-        let mut fields = CombineFields::new(
+        let mut op = TypeRelating::new(
             self.infcx,
-            ToTrace::to_trace(self.cause, expected, actual),
+            trace,
             self.param_env,
-            DefineOpaqueTypes::Yes,
+            define_opaque_types,
+            StructurallyRelateAliases::No,
+            ty::Invariant,
         );
-        fields.equate(StructurallyRelateAliases::Yes).relate(expected, actual)?;
-        Ok(InferOk { value: (), obligations: fields.into_obligations() })
+        op.relate(expected, actual)?;
+        Ok(InferOk { value: (), obligations: op.into_obligations() })
     }
 
     pub fn relate<T>(
@@ -242,19 +218,16 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     where
         T: Relate<TyCtxt<'tcx>>,
     {
-        let mut fields = CombineFields::new(
+        let mut op = TypeRelating::new(
             self.infcx,
             TypeTrace::dummy(self.cause),
             self.param_env,
             DefineOpaqueTypes::Yes,
-        );
-        fields.sub().relate_with_variance(
+            StructurallyRelateAliases::No,
             variance,
-            ty::VarianceDiagInfo::default(),
-            expected,
-            actual,
-        )?;
-        Ok(fields.goals)
+        );
+        op.relate(expected, actual)?;
+        Ok(op.into_obligations().into_iter().map(|o| o.into()).collect())
     }
 
     /// Used in the new solver since we don't care about tracking an `ObligationCause`.
@@ -266,60 +239,35 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     where
         T: Relate<TyCtxt<'tcx>>,
     {
-        let mut fields = CombineFields::new(
+        let mut op = TypeRelating::new(
             self.infcx,
             TypeTrace::dummy(self.cause),
             self.param_env,
             DefineOpaqueTypes::Yes,
+            StructurallyRelateAliases::Yes,
+            ty::Invariant,
         );
-        fields.equate(StructurallyRelateAliases::Yes).relate(expected, actual)?;
-        Ok(fields.goals)
+        op.relate(expected, actual)?;
+        Ok(op.into_obligations().into_iter().map(|o| o.into()).collect())
     }
 
     /// Computes the least-upper-bound, or mutual supertype, of two
     /// values. The order of the arguments doesn't matter, but since
     /// this can result in an error (e.g., if asked to compute LUB of
     /// u32 and i32), it is meaningful to call one of them the
     /// "expected type".
-    pub fn lub<T>(
-        self,
-        define_opaque_types: DefineOpaqueTypes,
-        expected: T,
-        actual: T,
-    ) -> InferResult<'tcx, T>
+    pub fn lub<T>(self, expected: T, actual: T) -> InferResult<'tcx, T>
     where
         T: ToTrace<'tcx>,
     {
-        let mut fields = CombineFields::new(
+        let mut op = LatticeOp::new(
             self.infcx,
             ToTrace::to_trace(self.cause, expected, actual),
             self.param_env,
-            define_opaque_types,
-        );
-        let value = fields.lub().relate(expected, actual)?;
-        Ok(InferOk { value, obligations: fields.into_obligations() })
-    }
-
-    /// Computes the greatest-lower-bound, or mutual subtype, of two
-    /// values. As with `lub` order doesn't matter, except for error
-    /// cases.
-    pub fn glb<T>(
-        self,
-        define_opaque_types: DefineOpaqueTypes,
-        expected: T,
-        actual: T,
-    ) -> InferResult<'tcx, T>
-    where
-        T: ToTrace<'tcx>,
-    {
-        let mut fields = CombineFields::new(
-            self.infcx,
-            ToTrace::to_trace(self.cause, expected, actual),
-            self.param_env,
-            define_opaque_types,
+            LatticeOpKind::Lub,
         );
-        let value = fields.glb().relate(expected, actual)?;
-        Ok(InferOk { value, obligations: fields.into_obligations() })
+        let value = op.relate(expected, actual)?;
+        Ok(InferOk { value, obligations: op.into_obligations() })
     }
 }
 

compiler/rustc_infer/src/infer/mod.rs

@@ -14,7 +14,6 @@ use region_constraints::{
     GenericKind, RegionConstraintCollector, RegionConstraintStorage, VarInfos, VerifyBound,
 };
 pub use relate::StructurallyRelateAliases;
-use relate::combine::CombineFields;
 pub use relate::combine::PredicateEmittingRelation;
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};

compiler/rustc_infer/src/infer/relate/combine.rs

@@ -1,4 +1,4 @@
-//! There are four type combiners: [TypeRelating], `Lub`, and `Glb`,
+//! There are four type combiners: `TypeRelating`, `Lub`, and `Glb`,
 //! and `NllTypeRelating` in rustc_borrowck, which is only used for NLL.
 //!
 //! Each implements the trait [TypeRelation] and contains methods for
@@ -20,56 +20,13 @@
 
 use rustc_middle::bug;
 use rustc_middle::infer::unify_key::EffectVarValue;
-use rustc_middle::traits::solve::Goal;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
-use rustc_middle::ty::{self, InferConst, IntType, Ty, TyCtxt, TypeVisitableExt, UintType, Upcast};
+use rustc_middle::ty::{self, InferConst, IntType, Ty, TypeVisitableExt, UintType};
 pub use rustc_next_trait_solver::relate::combine::*;
 use tracing::debug;
 
-use super::lattice::{LatticeOp, LatticeOpKind};
-use super::type_relating::TypeRelating;
 use super::{RelateResult, StructurallyRelateAliases};
-use crate::infer::{DefineOpaqueTypes, InferCtxt, TypeTrace, relate};
-use crate::traits::{Obligation, PredicateObligation};
-
-#[derive(Clone)]
-pub(crate) struct CombineFields<'infcx, 'tcx> {
-    pub infcx: &'infcx InferCtxt<'tcx>,
-    // Immutable fields
-    pub trace: TypeTrace<'tcx>,
-    pub param_env: ty::ParamEnv<'tcx>,
-    pub define_opaque_types: DefineOpaqueTypes,
-    // Mutable fields
-    //
-    // Adding any additional field likely requires
-    // changes to the cache of `TypeRelating`.
-    pub goals: Vec<Goal<'tcx, ty::Predicate<'tcx>>>,
-}
-
-impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
-    pub(crate) fn new(
-        infcx: &'infcx InferCtxt<'tcx>,
-        trace: TypeTrace<'tcx>,
-        param_env: ty::ParamEnv<'tcx>,
-        define_opaque_types: DefineOpaqueTypes,
-    ) -> Self {
-        Self { infcx, trace, param_env, define_opaque_types, goals: vec![] }
-    }
-
-    pub(crate) fn into_obligations(self) -> Vec<PredicateObligation<'tcx>> {
-        self.goals
-            .into_iter()
-            .map(|goal| {
-                Obligation::new(
-                    self.infcx.tcx,
-                    self.trace.cause.clone(),
-                    goal.param_env,
-                    goal.predicate,
-                )
-            })
-            .collect()
-    }
-}
+use crate::infer::{InferCtxt, relate};
 
 impl<'tcx> InferCtxt<'tcx> {
     pub fn super_combine_tys<R>(
@@ -281,50 +238,3 @@ impl<'tcx> InferCtxt<'tcx> {
         val
     }
 }
-
-impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
-    pub(crate) fn tcx(&self) -> TyCtxt<'tcx> {
-        self.infcx.tcx
-    }
-
-    pub(crate) fn equate<'a>(
-        &'a mut self,
-        structurally_relate_aliases: StructurallyRelateAliases,
-    ) -> TypeRelating<'a, 'infcx, 'tcx> {
-        TypeRelating::new(self, structurally_relate_aliases, ty::Invariant)
-    }
-
-    pub(crate) fn sub<'a>(&'a mut self) -> TypeRelating<'a, 'infcx, 'tcx> {
-        TypeRelating::new(self, StructurallyRelateAliases::No, ty::Covariant)
-    }
-
-    pub(crate) fn sup<'a>(&'a mut self) -> TypeRelating<'a, 'infcx, 'tcx> {
-        TypeRelating::new(self, StructurallyRelateAliases::No, ty::Contravariant)
-    }
-
-    pub(crate) fn lub<'a>(&'a mut self) -> LatticeOp<'a, 'infcx, 'tcx> {
-        LatticeOp::new(self, LatticeOpKind::Lub)
-    }
-
-    pub(crate) fn glb<'a>(&'a mut self) -> LatticeOp<'a, 'infcx, 'tcx> {
-        LatticeOp::new(self, LatticeOpKind::Glb)
-    }
-
-    pub(crate) fn register_obligations(
-        &mut self,
-        obligations: impl IntoIterator<Item = Goal<'tcx, ty::Predicate<'tcx>>>,
-    ) {
-        self.goals.extend(obligations);
-    }
-
-    pub(crate) fn register_predicates(
-        &mut self,
-        obligations: impl IntoIterator<Item: Upcast<TyCtxt<'tcx>, ty::Predicate<'tcx>>>,
-    ) {
-        self.goals.extend(
-            obligations
-                .into_iter()
-                .map(|to_pred| Goal::new(self.infcx.tcx, self.param_env, to_pred)),
-        )
-    }
-}